Flexible pitman



E. A. THURSTON.

FLEXIBLE PITMAN.

APPLICATION FILED DEC.5. I9l8.

atented Aug. 19,' 1919.

2 SHEETSSHEET l- INVENTOR ZZWZen/i. 171207529072,

E. A. THURSTON.

FLEXIBLE PITMAN.

APPLICATION FILED DEC.5. 191B.

1 3 1 3, 764: Patented Aug. 19, 1919.

2 SHEETS-SHEET 2.

' INVENTOR Ilmer1.lizzzn5?on WMTED STATE$ PAEENT OFFICE.

ELMEB A. THUBSTON, OF NORFOLK, NEBRASKA, ASSIGNOB, OF ONE-HALF T JAMES A. MASON, OF NORFOLK, NEBRASKA.

FLEXIBLE PITMAN.

1 313 764 Specification of Letters Patent. Patented Aug. 19, 1919. Application filed December 5. 1918 Serial No. 265.425.

To all whom it may concern: 4 and tapering gradually to its straight re- Be it known that I, ELMER A. THURs'roN, duced ends 4", the purpose of which will a citizen of the United States, at present represently appear. siding at Norfolk, in the county of Madison For effecting the tight connection of the 5 andState of Nebraska, have invented cerhelical spring to its cooperating rigid rod tain new and useful Improvements in Fleximember 5, the said rod is provided at its ble Pitmen, of which the following is a lower end with a threaded portion 50 and specification. an end abutment 5 so designed as to screw The improvement relates to that class of into and abut the upper reduced end 4: of

10 inventions found particularly useful on sewthe spring l. 5 ing machines and the like where consider- The upper or crank engaging end of the able difliculty is encountered in the use of or rod 5 is threaded as at' 51 and adapted to dinary pitmenbecause of jarring and knockbe threaded into the threaded aperture 22 ing of the parts and the stopping of the of a journal block 21.

5 machine on a dead center. A look nut 52 being provided to cooperate 7 To this end, I have designed a flexible pitwith the journal block 21, it will be readily man which entirely does away with all jarseenthat any slight adjustment necessary,

ring, knocking and continuous adjusting of when first applying the device, may be readparts and also the danger of the machine ily effected.

o stopping on a dead centerwith its possible I wish it here understood, however, that consequence of reversing the machine and after the first application and adjustment breaking a needle or the ruining of the maof the pitman, no further adjustment will terial being worked and which may be ever be necessary. readily attached to most of the conventional For connecting the spiral spring member 25 types of machines in use.- to the treadle 3 of the machine, I have pro- With other objects in view that will presvid'ed a nipple 6 designed to thread into the ently appear, my invention comprises those lower reduced spiral l of the said spring novel details of construction and combinawhich includes a collar or abutment 61 serv tion of parts specifically pointed out in the ing the dual purpose of abutting the lower 30 appended claims and illustrated in the acend of the spring and forming a shoulder companying drawings, in which: to engage the treadle 3 when thenipple por- Figure 1 is a side elevation of my invention 6 is inserted in the aperture 30 protion as operatively applied to a sewing mavided therefor in the treadle and is rigidly chine. 1 fastened therein, when the nut 7 is screwed 3-5 Fig. 2 is a detail side view and part sechome on the projecting threaded portion 62. tion of the parts that constitute my im- With the parts thus-connected and opproved attachment. eratively applied as illustrated in Figs. 1,

: Fig. 3 is a diagrammatical side view and 3 and 4, it will be seen that the device loses illustrates the manner in which the pitman none of the advantages of a strictly rigid 40 operates to throw its cooperating crank pin pitman and still readily operates to do away past its upper dead center. with the faults thereof and accomplishes ev- Fig. l 1s a similar view illustrating the cry purpose for which it is designed. passing of the lower dead center. With reference to Fig. 2 of the drawings,

In its practical application, my improved it will be seen that the stout spring has its 45 pitman may be utilized on any machine emspirals closely wound so as to leave but a bodying the usual power wheel 2 and its very slight space between the adjacent coils, crank pin 20 and the treadle 3 or other parts thus allowing for the necessary lateral f l8?1- which would serve the same purpose on that bility. of the same and also for the rigidity particular machine. necessary on the power stroke up and down,

60 In the drawings, the pitman is shown as as will presently appear.

applied to a sewing machine 1 and includes Owing to the peculiar construction and a stout helical spring 4 and a rigid rod 5. c nnection of the device, as clearly illus- The spring, which forms an essential feature trated in Figs. 3 and 4: of the drawings, it of my improvement, is spindle shaped, will be readily seen that, owing to the lateral 65 budged or enlarged midway its length as at flexing of the spring portion of the pitman, 110

it is impossible for the machine to knock,

portion, as shown, and tendsto throw the crank members past the dead center (indicated in dot and dash lines) from the point A to the point B where the down power stroke will start and the spring then would start'to flex, as indicated in Fig. 4, and accomplish the smooth passing of the crank from the point A to B over the lower dead center, and so on.

I want it here understood that this purpose is accomplished smoothly and evenly and in nowise causes an intermittent jerking of the power wheel To those experienced in the useof machines, another difliculty is known other than the stopping of the machine when in, operation and that is encountered when, after the machine has been purposely brought to a stop, it is again sought'to' start it. In ordinary machines, the trea'dle, pitman and crankwill in this case gravitate to the lower dead center and it is then necessary that the operator furiously spin the handwheeland apply foot power just at the right interval to again put the machine in motion.

My device entirely does away with this objectionable feature, since the parts are so designed and operate so that it is impossible for the crank to stop on the lower (or upper) dead center, since the flexing of the spring positively throws it past these centers and, in the use of my pitman, the crank would always stop at a point such as indicated in Fig. 1 or as in dotted lines on Fig. 4 according to the strength and rigidity of the spring, so that to start up the machine, all that is necessary is to apply pressure to the heel portion of the treadle, thusmaking it entirely unnecessary to use the hands at any time, consequently -mak1ngcareful work more safe easier.

What I clalm is: 1'. A pitman comprising a rod section havgreater diameter midway between the twoends than they are adjacent to the ends, a

stud having a threaded shank onto which one end of said spring is screwed, said rod having a threaded shank onto which the other end of said spring is screwed, substantially as shown and described.

3. In combination with the rotatable power crank and the reciprocable treadle of a pitman connecting the aforesaid part said pitman comprising a rod section pivoted to the crank and a spring section rigidly secured to the treadle, said spring section comprising a helical coil spring, the diameter of which is greater toward the middle than at the ends, and the coils of which normally lie in close juxtaposition, said helical spring and said 133d section being rigidly connected end to en 4. A pitman' consisting of a rod, a stud and a helical coil spring, said rod, said spring and said stud being in longitudinal alinement, said spring comprising a coil, one end of which is wound around a portion of said rod and the other end of which is wound around a portion of said stud, the coils of the spring between the ends thereof being of gradually increasing diameter toward the midlength of the spring whereby the greatest diameter of the spring will be approximately midway between the ends of the spring substantially as shown and de scribed.

Emma A; rngnns'ron. 

